Update is great - maximum volume limit is great (do you still need 1x/2x voltage mode though?). 44.1kHz on USB is great - most music is 44.1. Keep up the good work.
But, I have to say - with things like EQ headroom it becomes more and more complicated and doesn't make sense - keep adding buttons works only for some time.
And generally, the usability concept requires to rework to make the same functionality more simple and accessible.
Few suggestions:
1. Stop using menu function tabs + bottom tabs. There is no clear logic why one thing is in left tab, another in bottom one and some functions accessible in both.
2. Device connection tab should be eliminated - if I've connected BT device for sound - it should work with it. If there are 2 at the same time - let me choose by their BT name. But for most people it's only 1 - don't show them anything about it.
3. Use only 1 concept of functions access.
4. Use checkboxes instead of radio buttons where both things can work (like EQ preamp or charger actions).
5. Remember output level estimator settings per device, not per app.
6. Instead of EQ preamp + settings of pre/post amp just make this: NEVER allow digital clipping by any amp settings. Who wants that? Just always do digital preamp down to highest peak on EQ and always try to set back volume in analog on same xx dB. Limit maximum analog volume based on that, obviously.
7. Make some kind of digital normalizer with automatic instant limiter (allow to define delay of volume going up, instant going down to prevent clipping and dB of maximum amplification) - for low sensitivity high impedance headphones it's useful. Certainly, this thing should work before EQ.
8. Move help topics out of UI - (?) button was working great for that. If it's article - make it as a link, not a text in UI.
9. Resort things in UI - what USB DAC or jitter cleaner settings do in BT settings and why BT pairing is not in BT settings? Really - make the whole list of functions and 3 levels of grouping - tab, group, element. Rethink it from the beginning. It's time for that.
10. Remove this output lock - always have it locked. Considering dangers - automatic output selection is a bad function that nobody needs. Make simple selector - balanced/unbalanced and somewhere in power group add a checkbox for unbalanced power savings to use 1 amp only to save power.
11. Change charger actions to 2 dropdowns of what to do in case charger connected and disconnected: Keep State, On, Off.
12. Make checkbox "Set this phone volume to maximum automatically after ES100 connected" instead of source volume slider.
Anyway, avoid clutter - people who keep getting new functions maybe happy with new functions, but you need to sell more devices to new people and aside of apparent outlook change to fight with BTR3 - you really need to make app friendly for newcomers. Now it scares new people. But it's easy to fix.